Method for measuring subject distance

Abstract

An exemplary method for measuring a distance from a subject to a camera includes the following operations: focusing on the subject using the imaging system; illuminating an area on the subject using auxiliary light; capturing an image of the subject, the image having an illumination portion corresponding to the illuminated area; measuring the area of the illumination portion of the image; and calculating the subject distance based on the measured area.

1. A method for measuring a distance from a subject to an imaging system, comprising:
 focusing on the subject using an auto focus lens of the imaging system; 
 illuminating an area on the subject using an auxiliary light of the imaging system by emitting a cone of light; 
 capturing an image of the subject using an image sensor of the imaging system, the image comprising an illumination portion corresponding to the illuminated area; 
 measuring the area of the illumination portion of the image; and 
 calculating the distance from the subject to the imaging system according to the following formula:
     u= 2 VL tan( A )/(2 V tan( A ) −Y ); 
 
 wherein V represents the distance between the auto focus lens and the image sensor, L represents the distance between the auxiliary light and the auto focus lens, A represents a half cone angle of the cone of light, and Y represents the area of the illumination portion. 
 
     
     
       2. The method as claimed in  claim 1 , wherein the step of focusing on the subject using the imaging system is performed using a process selected from the group consisting of: a phase detection process and a contrast measurement process. 
     
     
       3. The method as claimed in  claim 1 , wherein the step of measuring the area of the illumination portion comprises:
 segmenting the captured image to detect a location of the illumination portion in the captured image. 
 
     
     
       4. The method as claimed in  claim 1 , further comprising the step of displaying the measured distance. 
     
     
       5. The method as claimed in  claim 1 , wherein the imaging system is selected from the group consisting of a digital still camera and a video camera. 
     
     
       6. The method as claimed in  claim 1 , wherein the imaging system comprises a digital signal processor and a micro-control unit, the digital signal processor being configured to process the captured images to obtain auto-focus data, the micro-control unit being configured to control the imaging system to perform an auto-focus function based on the obtained auto-focus data. 
     
     
       7. The method as claimed in  claim 6 , wherein the image sensor is selected from the group consisting of a charge coupled device and a complementary metal oxide semiconductor.